The invention relates to an all weather visual system for helicopters using a synthetic aperture radar, based on rotating antennas.
U.S. Pat. No. 3,896,466 teaches a system with real-aperture radar whose antennas are centrally mounted; while U.S. Pat. No. 4,924,299 teaches providing SAR systems with a navigation system. These embodiments, however, are not suitable for ROSAR (rotating synthetic aperture radar) designs. German patent document DE 39 22 086 C1, see also U.S. Pat. No. 5,451,957 from Sep. 19, 1995, of applicant teaches a ROSAR device in which at least one antenna for sending and receiving radar pulses is located at the end of a rotating arm, for example, a helicopter rotor or a turnstile above the rotor axis. The received signals are demodulated and stored temporarily, and then correlated with reference functions. A radar of this type can be used for on-line operation in real time, and after special modifications can be employed not only for assisting landings, but also for target interception and tracking. However, the adaptation of this type of system into an all weather visual system is heretofore unknown.
The object of the present invention is to increase the lateral resolution of an all weather visual system with good vertical resolution and to permit optimum flight using a radar image.
To achieve this object, the present invention provides an all weather visual system which combines and displays information from a ROSAR type radar sensor with information from the on-board navigation and flight systems to provide artificial vision for the pilot, with the radar utilizing the rotational movements of rotating arms.
FIG. 3 shows the system design of the all weather visual system for helicopters with different expansion possibilities according to the invention. The central component of the system is a radar sensor 9 with the associated radar processor/image processor/obstacle processor 8. Flight information in the form of symbols generated by the navigation computer/symbol generator is superimposed on the radar image and the obstacle display. This complex image is then sent to a cockpit display 10. The data generated by the precision gyros and acceleration sensors 11 for motion compensation can also be used simultaneously in the navigation computer 12 for position calculation. An optional radar altimeter 13 supplements barometric altitude measurement 15 and increases safety when landing. An autopilot system 14 increases pilot comfort for normal flight.
A system of this kind can also be combined with the navigation computer and obstacle processor in such fashion that when there is direct threat to the helicopter from an obstacle, the autopilot initiates suitable evasive maneuvers. For flight under instrument flight conditions, conventional radio navigation systems 16 are connected to the navigation computer. Additional positional accuracy for normal flight and landing can be achieved by integrating a satellite navigation system 17 (GPA, differential GPS, or relational GPS). Another logical supplement to the all weather visual system is a digital map system 18 with maps of roads and airports.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.